Q: We are living in an area that is having a drought. We were talking to a neighbor, and he said that he was thinking about upgrading his irrigation system to a smart system. I am not sure what a smart irrigation system does that our current system doesn’t do. We watch the weather and the rainfall and adjust accordingly. We have many plants that are drought-tolerant, and we let our lawn turn brown so we don’t use too much water, but I was wondering what you think of a smart irrigation system.
A: I think you are doing the right thing in checking this out. The typical old-fashioned irrigation controller is clock- and calendar-based. It turns the various irrigation zones on and off one at a time depending on what you have set it to do. For instance, it will run a zone for 20 minutes twice a week, or on even or odd days. It may be raining at that time, but the system doesn’t know that, and it runs anyway.
Just because your area allows watering on even or odd days doesn’t mean your plants need water on that day. I have seen many people waste water and money watering plants that didn’t need water but were getting watered because of the day on the calendar. I have also seen plants that really needed to be watered but didn’t get it because the day of the week was wrong.
Most people are not as diligent as you are. They set their system once or twice a season and let it run—usually at night, when they can’t even tell if it is working properly or not.
A smart controller has clock and calendar settings, but instead of you having to manually overrule it when you think the conditions are proper, the controller has sensors that can automatically do that. Some systems have weather sensors that check for rainfall totals, humidity, temperatures, wind speeds and solar radiation. These systems have computer programs that compare your weather with how plants use water in what is called the evapotranspiration rate. These programs have been developed on golf courses and farm fields, so the controller knows when your plants need water. The controller lets the zones run for the amount of time that your plants need and then shuts off the zones.
Some smart controllers use soil sensors that test how much water is in the soil. The controller doesn’t turn on a zone until the soil reaches a specific dryness level.
In either sensor style, the smart controller only turns on the system when the plants need the water instead of when the clock or calendar says so. The smart controller can also be set to even or odd days so you can follow the local watering rules. Both systems may also have a rain sensor that turns off the system if it is raining. Upgrading the controller and adding a few sensors will still allow you to use your current irrigation system.
Whether or not you get a new smart irrigation controller, I urge you to check your whole irrigation system monthly. Run each zone for just a minute and look to see if each of the heads is spraying the water properly. Check to see if it covers the areas it is intended to cover. Check to see if there is a damaged head that needs to be repaired or replaced. When the system is running at night or early in the morning, you might miss a head that was damaged by a lawnmower and is sending a fountain up instead of spraying where it is supposed to go.
